PROJECT SUMMARY/ABSTRACT Adults with Alzheimer’s diseases and related dementia (ADRD) are among the most vulnerable individuals from the pandemic. Both formal and informal care for adults with ADRD has been profoundly affected by the Covid-19 pandemic. Despite the need of frequent hands-on care for these adults due to their limitations in physical and cognitive functioning, in-home care services are limited and nursing home care has been risky during the pandemic. The social and economic circumstances of many families also have been changed due to the pandemic and hence their resources to care for a family member with ADRD. Disrupted care for adults with ADRD may have adverse health consequences that may last beyond the pandemic period. A better understanding of the effects of the pandemic on the dynamics between formal and informal care is critically important to address unmet care needs for adults with ADRD during and after the pandemic. We will first create a contextual measure of exposure to the pandemic (pre-, low-, high-, post-exposure) by taking into account the infection risks of the virus in the local area and develop a tailored geographic boundary for each individual that encompasses health and healthcare implications more directly relevant to the individual. We will then examine differences in healthcare utilization associated with the level of exposure to the pandemic. We will also assess the mediating and moderating role of formal and informal care resources (e.g., hospital capacity, family availability) in the pandemic’s effects on healthcare utilization. It will then examine the extent to which health, mortality, and healthcare costs of adults with ADRD were affected by the exposure to the pandemic, including potential differential effects across demographic (gender, racial/ethnic) and economic groups. The proposed study uses an innovative, comprehensive approach to assess the Covid-19 pandemic effects. It will develop a fine-grained contextual measure of exposure to the pandemic by using a daily infection risk in a local area (tract, ZIP code, county) where an adult with ADRD lives and addressing spillover effects of neighboring areas. It provides a nuanced understanding of the pandemic’s effect on healthcare utilization by incorporating information on the time-course of dementia (exposure at the onset vs. exposure during the subsequent years of dementia). The study will provide important data on the underlying mechanisms of the pandemic’s effect on healthcare utilization and health, and will identify sociodemographic and economic groups that are the most affected. Therefore, it will inform health policies and intervention programs aimed at improving healthcare systems to mitigate adverse effects of the pandemic and to reduce disparities in healthcare and health outcomes. 1